Definition of Opaque

3. Adjective. (figuratively) Unclear, unintelligible, hard to get or explain the meaning of ¹

4. Adjective. (figuratively) Obtuse, stupid. ¹

5. Adjective. (computing) Describes a type for which higher-level callers have no knowledge of data values or their representations; all operations are carried out by the type's defined abstract operators. ¹

6. Noun. (obsolete poetic) An area of darkness; a place or region with no light. ¹

2.A Treatise on Chemistry by Henry Enfield Roscoe, Carl Schorlemmer (1883)"opaque AND COLOURED GLASS. 293 Transparency is certainly the most important
property of glass, and yet for some purposes translucent or even opaque "lass is ..."

3.The American Journal of the Medical Sciences by Southern Society for Clinical Investigation (U.S.) (1847)"The vitreous, so far from being le?s soluble in water than the opaque acid, as
slated by chemists, is, on the contrary, much more soluble. ..."

5.Petrographic Methods: The Authorized English Translation of Part I by Ernst Weinschenk, Robert Watson Clark (1912)"opaque Minerals Included with the opaque minerals are those which are ordinarily
not transparent in ... Some opaque minerals are cubic and some hexagonal. ..."